This invention relates generally to muscle exercise and rehabilitation apparatus, and more particularly, is directed to such apparatus in which controlled rotational motion is converted to controlled linear motion to evaluate the entire body for lifting performance, particularly with respect to work fitness and disability.
In many cases, it is desirable to simulate the demands of the workplace for screening or training purposes. Specifically, it is desirable to measure physical capacity by measuring strength in the context of specific job requirements. This is particularly important in view of the fact that the National Institute for Occupational Safety and Health (NIOSH) has indicated that substantial strength is required in approximately one-third of all jobs in the United States.
In addition, overexertion on and off the job is a major cause of lower back pain. This entails a significant amount of lost time. Thus, the incidence of lower back pain with different musculoskeletal disorders and injuries is high in the United States. Accordingly, it is also desirable to impose demands on the musculoskeletal system of the spine in order to stimulate metabolic, ligamentous, facial, cardiovascular, and neuromuscular adaptations resulting in performance enhancement, and to also engage motor learning mechanisms for performance enhancement.
The above simulation and performance enhancements are preferably performed under loaded or velocity controlled conditions. In particular, it is desirable to reproduce lifting and lowering of weights when task parameters are controlled and measured by a force sensing and generating device interfaced with a computer system. Such lift simulation would primarily involve the extensor musculature and the axial/proximal musculoskeletal control system of the body. In such case, muscle group strength, power and endurance necessary for occupational task performance can be quantified.
Various exercising machines, such as those designated by "Universal", "Nautilus", "Cybex" and "Kin/Com", are well known in the art.
One of the first of these machines was the "Universal" exercising machine which uses a pulley-weight system, whereby the weights added to the pulley system can be varied by the user. With such apparatus, however, there are no controls over the manner, that is, the speed of movement and the torque applied by the user, in overcoming the weight load. It is only necessary that the user apply a force that is greater than the weight load through the pulley system. As such, the "Universal" apparatus is similar to a free weight system. An apparatus of the "Universal"-type is described in U.S. Pat. No. 4,691,916 to Voris. See also U.S. Pat. No. 4,339,125 to Uyeda et al.
U.S. Pat. No. 477,613 to Sundh discloses a similar weight training machine which uses a pulley system. However, there is no translation of a controlled rotational movement to a controlled linear movement for the purpose of clinical evaluations.
U.S. Pat. No. 4,620,703 to Greenhut merely describes a drum and pulley exercise machine that provides linear motion. However, there is no controlled rotational motion that is converted to linear motion for the purpose of clinical evaluations. See also U.S. Pat. No. 4,529,196 to Logan et al. and U.S. Pat. No. 4,728,102 to Pauls.
With all of such apparatus, however, there is no controlled movement of the velocity or torque of the linear arm, whereby clinical testing can be performed to simulate imposed work demands and/or for performance enhancement.
The "Nautilus" apparatus was developed to overcome some of the deficiencies of the "Universal" machine by providing a fixed path of movement of the respective arms thereof so that the latter follow respective paths designed for better muscle isolation during exercise. The "Nautilus" apparatus, rather than using a pulley-weight system, uses a novel cam arrangement. However, as with the "Universal" machine, the "Nautilus" apparatus does not control the speed of movement or resistive torque applied to the arm.
The "Cybex" apparatus, as exemplified in U.S. Pat. No. 3,465,592, recognized that the muscle is not equally powerful throughout its entire range of motion. The "Cybex" apparatus provides a motor connected through a gearing system to regulate the exercise arm of the machine so that it travels with a constant velocity, thereby taking into account the different strengths of the muscle during different angular extensions thereof.
Although the "Cybex" apparatus provides distinct advantages over the aforementioned "Universal" and "Nautilus" apparatus, the "Cybex" apparatus fails to provide necessary functions for truly accurate and corrective exercise and rehabilitation. In this regard, the "Cybex" apparatus uses a motor with two clutches. The arm of the apparatus is movable freely until the planetary speed of the gearing therein is reached, whereupon an impact resistive force is met by the user. This impact resistive force, of course, is undesirable, particularly from a rehabilitation standpoint. In addition, the "Cybex" apparatus does not provide for any translation of a controlled rotational motion to a linear motion, whereby accurate simulations can be provided.
U.S. Pat. No. 4,235,437 discloses a robotic exercise machine which uses a computer to regulate the motion of an exercise arm in response to software programmed into the machine and in response to the force applied to the arm by the user as detected by a strain gauge at the end of the arm. By means of hydraulic cylinders and solenoid controlled valves, movement of the arm can be accurately controlled. However, the equipment provided in U.S. Pat. No. 4,235,437 is relatively complicated and requires expensive computer equipment and a complex linkage system. Further, because the equipment is computer controlled, the user must spend some time programming the computer with the desired settings before exercising. This, of course, is time consuming and detracts from the exercise.
It is to be appreciated that, with muscle exercise and rehabilitation apparatus, it is necessary that movement of the arm be smooth in all modes of operation, particularly when simulating work conditions or imposing demands that result in performance enhancement. A problem with computer controlled apparatus is that the computer must make various samplings and computations, and thereafter makes corrections that are necessary. Although computer time is generally considered fast, the amount of time necessary for the computer to perform such operations and then control the mechanical and hydraulic devices of the apparatus may not result in smooth movement of the exercise arm, particularly at small loads.
There is also known a muscle exercise and rehabilitation apparatus sold by Chattecx Corporation of Chattanooga, Tenn. under the name "Kin/Com" which provides a computer controlled hydraulic system that monitors and measures velocities, angles and forces during muscular contractions. A load cell is provided to measure the force at the point of application, with an accuracy of 4 ounces. However, this apparatus, being computer controlled, suffers from the same problems discussed above with respect to U.S. Pat. No. 4,235,437. Further, there is no conversion of controlled rotational motion to a linear motion for the purposes described above.
U.S. Pat. Nos. 3,848,467 and 3,869,121 each disclose an exercise machine in which a user applies a force to an arm which is coupled to a drive shaft, the latter being driven by a servo motor through a speed reducer. A brake is connected to the servo motor through the speed reducer, although in the embodiment of FIG. 3, a permanent magnet servo motor is used as both the powering means and the brake. A speed and direction sensor is connected with the drive shaft, the servo motor or the speed reducer, and supplies a signal to a comparator, corresponding the direction and speed of the arm. Another input of the comparator is supplied with a signal from a speed and direction programmer, corresponding to a desired speed and direction of movement of the arm. The comparator controls the powering means and the brake in response to these signals to regulate the system speed, responsive to varying exercises force applied to the arm during both concentric and eccentric muscular contractions.
With these latter Patents, however, there is a drum and pulley arrangement, which is not conducive to simulating imposed demands of the workplace for screening or training, and is not conducive to performance enhancement in accordance with the demands as set forth above. Further, there is no disclosure of any conversion of a controlled rotational motion to a linear motion for such purposes.
In order to overcome problems with the latter patents, there is disclosed in U.S. Pat. No. 4,628,910, having a common assignee herewith and the entire disclosure of which is incorporated herein by reference, a muscle exercise and rehabilitation apparatus in which the servo motor is used to move the arm at all times.
Specifically, as disclosed therein, in the concentric isokinetic mode of operation, the arm is controlled to move with a regulated velocity in the direction of force applied by the user, for both flexion (bending) and extension (unbending) of the limb. For example, in a knee extension/flexion operation, where a cuff at the end of the arm is brought from a vertical to a horizontal position of the user, the servo motor which controls movement of the arm, is driven at a velocity dependent upon the force applied by the user, and in the same direction as the applied force, until a predetermined clamp velocity is reached. Once the predetermined clamp or set velocity is reached, the servo motor drives the arm at a predetermined constant velocity, whereby the arm moves with a constant velocity in the direction of force applied by the user. Thus, if the force applied by the user is too great, that is, will normally drive the arm at a velocity greater than the clamp velocity, the servo motor only drives and/or allows the arm to move at the predetermined clamp velocity. If the user stops applying the force, the arm will stop moving.
During the return movement, where the cuff is brought from the horizontal position to the lower vertical position, during flexion, the user must apply a force in the downward direction in order for the cuff to be moved downwardly. The servo motor moves the arm and the cuff, initially at a velocity dependent upon the downward force applied by the user. Once the velocity reaches a predetermined clamp velocity, the servo motor drives the arm at the predetermined velocity, whereby the arm moves with a constant velocity in the direction of force applied by the user. As with extension, if the user stops applying the force, the arm will cease moving with a constant velocity and come to a full stop.
Thus, with such apparatus, for flexion and extension, the servo motor drives the arm. The user does not move the arm but merely provides a measured force by which the servo motor is controlled.
In the eccentric isokinetic mode of operation, the arm is controlled to move with a regulated velocity in the direction opposite to the direction of force applied by the user, for both flexion and extension of the limb. In one embodiment, the range of speeds is much smaller than that in the concentric isokinetic mode in order to prevent harm to the user. However, again, for both flexion and extension, the servo motor drives the arm.
In the passive or oscillation mode, the arm is caused to oscillate by the servo motor at a constant speed, regardless of the force applied by the user. If there is a force applied by the user, regardless of the direction of such force (either concentric or eccentric), which would cause the arm to change its speed of oscillation, the servo motor controls the arm to maintain the constant speed.
In all of the above modes, it is the servo motor which moves the arm in response to the sensed velocity and/or predetermined force applied to the arm. The user does not move the arm. Because the servo motor is used to move the arm at all times, movement of the arm can be linearly controlled in response to the force applied thereto for forces within the range of 0-400 foot-pounds.
With such apparatus, circuitry is provided for limiting the angular range of motion of the arm.
However, such apparatus is intended to only apply a rotational movement to the arm. Therefore, it is difficult to simulate imposed demands of the workplace or provide performance enhancement by demands imposed on the musculoskeletal system or by engaging motor learning mechanisms.
U.S. Pat. No. 4,691,694 is a Continuation-In-Part of U.S. Pat. No. 4,628,910, and the entire disclosure thereof is incorporated herein by reference. U.S. Pat. No. 4,691,694 discloses a more advanced version of the apparatus of U.S. Pat. No. 4,628,910, but it also suffers from the same deficiencies with regard to the purposes set forth above.